Geiser Fritz, Pavey Chris R
Centre for Behavioural and Physiological Ecology, Zoology, University of New England, Armidale, NSW, 2351, Australia.
J Comp Physiol B. 2007 Nov;177(8):885-92. doi: 10.1007/s00360-007-0186-z. Epub 2007 Aug 3.
Australian deserts are characterized by unpredictability, low primary productivity, and high temperature fluctuations. Despite these adverse conditions the diversity of small insectivorous marsupials of the family Dasyuridae is surprisingly high. We quantified the thermal biology of the dasyurid Pseudantechinus madonnellensis (body mass approximately 30 g) in the wild to gain some understanding of whether the success of dasyurids in the arid zone may be related to some extent to their use of energy conservation strategies. In winter, most free-ranging Pseudantechinus frequently (58.3% of 131 animal days) entered daily torpor after midnight (mean 0157 hours) in rock crevices when outside ambient temperatures (T (a)) were low. Most animals remained torpid until the next morning when they moved while still torpid from rock crevices to sun-exposed basking sites. We visually observed basking during rewarming from torpor (mean commencement at 0943 hours) at body temperatures (T (b)) as low as 19.3 degrees C when radiant heat was high and T (a) was rising. Basking continued for the rest of the day. Torpor use was not strongly correlated with T (a), but the temporal organization of daily torpor and activity were apparently linked to the thermal characteristics of basking sites. Our study suggests that by frequently employing daily torpor and basking and by appropriately coordinating their thermal biology with that of specific locations in their environment, Pseudantechinus can reduce daily energy expenditure and thus can live and reproduce in a challenging environment. It is likely that the success of other small dasyurids and perhaps many other small mammals living in deserts is linked to employment of torpor and basking for energy conservation.
澳大利亚沙漠具有不可预测性、初级生产力低和温度波动大的特点。尽管存在这些不利条件，但袋鼬科小型食虫有袋动物的多样性却出奇地高。我们对野生的袋鼬属马多内袋鼬（体重约30克）的热生物学进行了量化，以了解袋鼬科动物在干旱地区的成功生存是否在一定程度上与其采用的能量节约策略有关。在冬季，大多数自由活动的马多内袋鼬（在131个动物日中有58.3%）在午夜后（平均0157时），当外界环境温度（Ta）较低时，会频繁地进入每日蛰伏状态，它们会在岩石裂缝中蛰伏。大多数动物会一直蛰伏到第二天早上，然后在仍处于蛰伏状态时从岩石裂缝移动到阳光照射的晒太阳地点。我们在动物从蛰伏状态复温期间（平均开始时间为0943时）进行了目视观察，当辐射热较高且Ta上升时，动物在体温（Tb）低至19.3摄氏度时就开始晒太阳。晒太阳会持续一整天。蛰伏的使用与Ta没有很强的相关性，但每日蛰伏和活动的时间安排显然与晒太阳地点的热特性有关。我们的研究表明，通过频繁采用每日蛰伏和晒太阳，并通过将其热生物学与环境中的特定位置进行适当协调，马多内袋鼬可以减少每日能量消耗，从而能够在具有挑战性的环境中生存和繁殖。其他小型袋鼬科动物以及可能许多生活在沙漠中的其他小型哺乳动物的成功生存，很可能与采用蛰伏和晒太阳来节约能量有关。
